Stihl 4-mix engines

[Rustyoldtractor]

Tripp Batts in Stanton

[Rustyoldtractor]

Tomtop, does yours rev for the full range of the throttle?

[Watercourse management]

I'm on my third km 4 mix now they seem to last about four to five years with me before the end of the exhaust valve breaks of and holes the piston,only ever used sthil red oil?

[Rustyoldtractor]

I put the premix Ultra in, but the shop was happy to sell the red stuff for it. When these things are running right do they rev freely? Mine seems to choke above half throttle. I would say it was running rich, but there is no sign of smoke, and the dealer says its fine. Yeah right!

[BishBashBosh]

...When these things are running right do they rev freely? Mine seems to choke above half throttle. I would say it was running rich, but there is no sign of smoke, and the dealer says its fine. Yeah right!

They sound very different to a traditional 2 stroke, so assessing performance by ear can be misleading.

 

It might be bouncing off the rev limiter or as you suspect over fueling and not accelerating. Put a tacho on it and you'll KNOW what it's revving to (Manual states 10 500rpm) and what the appropriate course of action is. HTH

[Rustyoldtractor]

Thanks BBB. Ill pass that on to Tripp Batts. I was surprised at the exhaust note produced by the machine. As you say, a lot different to my other 2 strokes.

[Rustyoldtractor]

Would I be right in assuming that if max revs are not achieved before WOT it needs leaning out? Conversely, if max revs come in well before WOT it needs to be richer?

[Rustyoldtractor]

Hum, it seems that Tripp Batts are saying its fine by running it up with no attachment fixed, whilst I'm running it with the strimmer head. Surely the engine needs a load on it to say its fine?

[Tomtop]

I was guessing Tripp batt. Make them put a strimmer head in. They will say they can't but tell them to go ask Ian that normally works.

[Tomtop]

I use Tripp a lot. If they are being funny I must be close to you and happy help.